Figure 1. Pacific Giant Salamander (Credit: Sierra Nystrom)
Figure 2. The Mack Creek study site is located in the HJ Andrews Experimental Forest, Oregon. (Credit: Dana Warren)
Figure 3. Mack Creek, HJ Andrews Experimental Forest, OR (Credit: Oregon State University)
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| Channel Class | Clear Cut | Old Growth |
|---|---|---|
| Cascade | 247 (55%) | 201 (45%) |
| Pool | 31 (41%) | 45 (59%) |
| Side Channel | 90 (55%) | 74 (45%) |
There is not a significant association between forest condition (old growth/clear cut) on where in the channel salamanders are found (pool/side-channel/cascade) for salamanders sampled in 2017. (\(\chi\)2(2) = 5.54, p = 0.063).
There is not enough evidence to conclude that mean Pacific Giant Salamander size in the clear cut section of Mack Creek in 2017 (7.78 \(\pm\) 9.9, n = 368) differed significantly from mean Pacific Giant Salamander size in the old growth section of Mack Creek in 2017 (6.58 \(\pm\) 8.96, n = 327) by a two-sided, two sample t-test (t(692.79) = -1.67, p = 0.096). In addition, the effect size between mean sizes is negligible (Cohen’s d = 0.13).
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Figure 7. Insert Caption
Mean salamander weight (g) differed significantly between the three creek channel classifications (pool, cascade, side-channel) by a one-way ANOVA test F(2, 684) = 4.22, p = 0.015). However, Post-hoc Tukey’s HSD revealed that only the side-channel and pool channel classifications differed significantly (p =0.0166225). Though mean salamander weight differed significantly between the pool and side-channel sections of Mack Creek, the effect size is small (Cohen’s d = 0.21).
Gregory S. V. 2016. Aquatic Vertebrate Population Study in Mack Creek, Andrews Experimental Forest, 1987 to present. Environmental Data Initiative. https://doi.org/10.6073/pasta/5de64af9c11579266ef20da2ff32f702. Dataset accessed 11/27/2019.